1. Field of the Invention
The invention relates to a method of recovering glass and metal from solid residues produced in refuse incineration plants and also to an apparatus for carrying out the method.
2. Discussion of the Background
In refuse incineration plants from 30 to 35% of the amount of refuse charged is produced as slag. The latter contains up to 10% of unburned organic materials and metallic constituents. The iron parts are removed from the slag by magnetic separators, whereupon the residual slag can be processed into building materials. However, since the residual slag still contains water-soluble constituents, its use leads to groundwater pollution. All other solid residues produced in a refuse incineration plant, such as boiler fly-ash and filter dust, must be taken to special tips.
The known wet deslagging of the solid residues does not result in complete removal of the water-soluble fractions and pollutes the water.
The conversion of waste materials, including ash, from refuse incineration plants into glass is known from EP-A2 0 359 003 and DE-C 38 41 918. The waste materials must in that case be prepared before being melted down; in particular they must be freed from metal constituents. Residues produced in a hot state, such as slag, must therefore first be cooled. The removal of iron irregularly distributed in slag from refuse incineration plants is practically never completely successful. The residual iron is deposited in the furnace during the production of glass and brings the operation to a standstill. The complicated preparation of the slag and the expensive operation of the furnace compel the separation of the refuse incineration plant and the melting plant.
In order to avoid environmental pollution through the gases produced during the melting with known techniques, it is necessary to employ complicated methods and expensive equipment.
In addition, quite large amounts of additives have to be used for the glass melt, and therefore large amounts of energy are required for the melting process. The additives considerably increase the amount of glass stored in tips.